This disclosure relates to fan blades that utilize composite materials and modifications to the composite material to reduce damage from the impact of objects striking the fan blades, such as birds.
Fan blades for gas turbine engines are typically designed to meet regulations relating to the impact of foreign objects against the fan blades while in operation. For example, regulations require a commercial airline engine to be capable of ingesting a medium-sized bird while allowing for continued operation or safe and orderly shutdown of that engine. Further, regulations also require that fan blades must resist cracking from nicks and dents caused by small debris such as sand and rain.
The design requirements may be especially challenging for fan blades constructed of fiber composite materials that may be less ductile than fan blades formed of metallic alloys. Fiber composite fan blades must have a greater thickness than metal or titanium fan blades to meet the bird strike regulations due to low strain tolerance of fiber composites. However, increasing the blade thickness reduces fan efficiency and offsets a significant portion of weight savings gained from using fiber composite materials.
Accordingly, it is desirable to provide a fiber composite material with greater strain tolerance and a fan blade comprising the fiber composite material with greater strain tolerance.